This invention relates generally to gas turbine engines, and more particularly to the extraction of air from a compressor of a gas turbine engine.
Gas turbine engines typically include a multistage axial flow high pressure compressor which supplies high pressure air to a combustor. The compressor includes multiple stages. Each stage is composed of a stationary component referred to as a stator and a rotational component, which adds work to the system referred to as a rotor. A portion of compressed interstage air may be extracted for turbine section cooling, airframe pressurization, anti-icing, and other uses. Because work is added to air as it flows through each stage of the compressor, it is desirable to extract, or bleed, air from the compressor after the minimum number of stages.
Small quantities of air can be extracted through bleed openings between stator vanes. As the volume of air required to be extracted from the compressor increases, the required area of the openings increases until the openings are too large to be located between the vanes. To extract large volumes of air, multiple rows of openings typically must be located downstream from a vane row. The axial spacing between the trailing edge of the vane row and the leading edge of the next blade row typically must be increased in order to accommodate the bleed openings. This results in an increase in the overall compressor length which adds weight and cost to the engine.
Accordingly, it would be desirable to provide for extraction of large volumes of interstage compressor air without increasing the length of the compressor.